CN116502545A - Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure - Google Patents

Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure Download PDF

Info

Publication number
CN116502545A
CN116502545A CN202310755376.2A CN202310755376A CN116502545A CN 116502545 A CN116502545 A CN 116502545A CN 202310755376 A CN202310755376 A CN 202310755376A CN 116502545 A CN116502545 A CN 116502545A
Authority
CN
China
Prior art keywords
grating
coupling
angle
grating structure
eta
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202310755376.2A
Other languages
Chinese (zh)
Other versions
CN116502545B (en
Inventor
王宁
周宁
吴达坤
王建伟
顾奕彤
于飞
于春雷
胡丽丽
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou Institute of Advanced Studies of UCAS
Original Assignee
Hangzhou Institute of Advanced Studies of UCAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hangzhou Institute of Advanced Studies of UCAS filed Critical Hangzhou Institute of Advanced Studies of UCAS
Priority to CN202310755376.2A priority Critical patent/CN116502545B/en
Publication of CN116502545A publication Critical patent/CN116502545A/en
Application granted granted Critical
Publication of CN116502545B publication Critical patent/CN116502545B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/27—Design optimisation, verification or simulation using machine learning, e.g. artificial intelligence, neural networks, support vector machines [SVM] or training a model
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N3/00—Computing arrangements based on biological models
    • G06N3/12—Computing arrangements based on biological models using genetic models
    • G06N3/126—Evolutionary algorithms, e.g. genetic algorithms or genetic programming
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/06—Multi-objective optimisation, e.g. Pareto optimisation using simulated annealing [SA], ant colony algorithms or genetic algorithms [GA]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/10—Numerical modelling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Evolutionary Computation (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Biophysics (AREA)
  • Computer Hardware Design (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Software Systems (AREA)
  • Evolutionary Biology (AREA)
  • Bioinformatics & Computational Biology (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Mathematical Optimization (AREA)
  • Computational Linguistics (AREA)
  • Mathematical Analysis (AREA)
  • Computational Mathematics (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Medical Informatics (AREA)
  • Physiology (AREA)
  • Genetics & Genomics (AREA)
  • Biomedical Technology (AREA)
  • Pure & Applied Mathematics (AREA)
  • Data Mining & Analysis (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Computing Systems (AREA)
  • Mathematical Physics (AREA)
  • Optical Integrated Circuits (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

The genetic algorithm, application and microstructure optical probe for the wide-angle coupling structure comprises the following steps of S1, taking the height H, the period lambda, the grating width w, the refractive index n_g of a grating material and the incident angle theta in the grating structure as variables, taking the mean square error of the grating coupling efficiency eta and a target value eta_ideal as a fitness function, changing the value of a target diffraction order a_ (+1) and the coupling efficiency eta of the optical probe through different combinations of parameters of each grating structure, and outputting the optimized grating structure through steps S1-S8. The genetic algorithm, application and microstructure optical probe for the wide-angle coupling structure set the fitness function related to the diffraction order working efficiency according to various factors and requirements such as target wavelength, incidence angle, waveguide structure and the like, and iteratively improve the diffraction order value, so that the diffraction efficiency of a specific diffraction order is improved, the coupling efficiency is optimized, and the efficient coupling in/out of the optical waveguide of the wide angle of a light beam is realized.

Description

Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure
Technical Field
The invention relates to the technical field of wide-angle optical signal detection, in particular to a genetic algorithm, application and microstructure optical probe for a wide-angle coupling structure.
Background
Optical fiber is used as a light wave transmission medium, and has been widely used in modern technology because of its advantages such as flexibility, high bandwidth, and remote measurement. The optical fiber probe prepared by the optical fiber is used as a micro-nano optical waveguide structure, not only inherits the intrinsic advantages of the optical fiber, but also can realize the regulation and control of optical signals on the micro-nano scale, conforms to the development trend of miniaturization and integration in recent years, and has good application prospect in the micro-nano optical field. Particularly, in many fields such as silicon-based integrated optoelectronic chips, scanning near-field microscopes, wide-angle endoscopes, etc., the optical fiber probe can realize efficient collection of the incident optical signal, and higher optical coupling efficiency generally determines better system performance. Therefore, how to use the optical waveguide probe to perform efficient optical coupling is an important issue in the fields of photoelectric detection, optical communication and the like.
The fiber optic probe body portion is comprised of a fiber optic waveguide substrate. Common fiber probes may be tapered fibers or flat fibers. When incident light strikes the fiber end face, only light within a specific range of angles of incidence can be coupled by the probe. The coupled light propagates through the waveguide, and at the other end of the fiber-optic probe, detection of the coupled light can be achieved using a tool such as an optical power meter. However, a large pain point based on bare fiber signal detection is large signal loss and low coupling efficiency at wide angle incidence. For example, at 1550nm wavelength, the numerical aperture NA of the communication single-mode fiber SMF-28 is only 0.14, and the coupling efficiency at wide angle (> 30 DEG) incidence is lower than 10-16. For this reason, a typical research scheme is to increase the numerical aperture by increasing the difference between the refractive index of the core and the refractive index of the cladding, thereby improving the coupling efficiency. Such as void microstructured optical fibers or soft glass material filled optical fibers. However, the scheme changes the structure of the optical fiber, greatly challenges the drawing process, and easily causes the quality problems of cross section deformation, structural fracture and the like; meanwhile, the mode types of the high NA optical fiber are increased (> 1000), the mode field is uncontrollable, phenomena such as beat frequency among modes and the like are easy to cause, and the signal transmission quality is reduced.
For this reason, an optical probe solution for improving the coupling efficiency of an optical waveguide based on a micro-nano structure has been sequentially proposed and intensively studied. The optical probe based on micro-nano structure enhancement comprises a main body, an optical fiber waveguide substrate, a coupling structure and the like. Wherein the coupling structure is based on grating diffraction effect, and the grating formula mλ=d (sin α±sin β), wherein m is diffraction order, λ is incident wavelength, d is grating period, α is incident angle, and β is diffraction angle, and the specific diffraction order working efficiency (such as +1 order diffraction order a) of incident light at wide angle is improved by regulating and controlling grating parameters such as filling coefficient, period, refractive index, etc +1 ). The coupling structure is prepared on the end face of the optical fiber waveguide by micro-nano processing methods such as electron beam etching, two-photon polymerization and the like, so that the scheme has the advantages of non-invasiveness, no damage, universal processing technology and the like. For example, yermakov et al, russian university of ITMO, propose a ring grating microstructure-based optical probe with a wide angle incidence 70 ° coupling efficiency of up to about 14% which is the highest current wide angle coupling record (ACS Photonics 7 (10), 2834-2841). But the probe can only work at a single angle (70 DEG) and a single wavelength (1550 nm) and is far from the practical application requirement (covering the incident angle range of 0-85 DEG)And average coupling efficiency curve>10%) are far from each other.
In order to continuously improve the working efficiency of the coupling structure of the optical probe, the filling coefficient, period, refractive index and other multidimensional parameters of the microstructure need to be designed and optimized in a targeted manner. However, the traditional microstructure design flow is tedious and low in efficiency, the geometric parameters are manually adjusted, and the performance of the microstructure is improved in an iterative mode. The process is time-consuming and labor-consuming, and a numerical simulation program with a large amount of computation resources is needed; in addition, in the face of a multi-parameter multi-target scene, the limited mental capacity of a human is difficult to control and design freedom, so that the designed structure has poor and satisfactory functions and cannot meet the actual application demands.
In general, the coupling structure facing the wide-angle incident light probe has low coupling value and small collection angle, and cannot meet application requirements; and the traditional design flow is tedious, low in efficiency, and cannot be used for optimizing the performance of a specific application scene.
Therefore, how to solve the problems of poor design effect and the like of the novel microstructure enhanced optical probe coupling structure is a problem to be solved urgently by those skilled in the art.
Disclosure of Invention
A first object of the present invention is to provide a genetic algorithm for a wide-angle coupling structure, which aims at the problems in the prior art.
For this purpose, the above object of the present invention is achieved by the following technical solutions:
a genetic algorithm for a wide-angle coupling structure, comprising the steps of:
step S1, using the height H, the period lambda, the grating width w, the refractive index n_g of a grating material and the incident angle theta in a grating structure as variables, using the mean square error of the grating coupling efficiency eta and a target value eta_ideal as an fitness function, and changing the value of a target diffraction order a_ (+1) and the coupling efficiency eta of the optical probe through different combinations of parameters of each grating structure;
step S2, using electromagnetic field simulation software to obtain a_ (+1) of the grating structure and the coupling efficiency eta of the optical probe, and calculating a fitness function F=MSE (eta, eta_ideal);
step S3, judging whether the coupling efficiency eta of the current grating structure reaches a set value eta_ideal, if so, directly outputting the current grating structure, and if not, entering step S4;
step S4, screening operation is carried out, and a new grating structure population is formed by selecting a grating structure with high coupling efficiency eta from the previous grating structures according to 50% probability so as to reproduce and obtain a next generation grating structure population, wherein the grating structure with high coupling efficiency eta refers to a grating structure with the average value eta' of the coupling efficiency of the previous generation;
step S5, performing cross operation, randomly selecting two or more grating structure parameters from a grating population, inheriting the high coupling efficiency eta characteristic of the current grating to the next generation through the exchange combination of parameter variables, thereby generating a new excellent grating structure combination, wherein the coupling efficiency eta of the new excellent grating structure is higher than the average value eta' of the coupling efficiency of the previous generation;
s6, performing mutation operation, wherein in the current grating population, parameters or parameter combinations of a certain grating structure are randomly changed so as to expect to generate more grating structures;
step S7, calculating a fitness function f=mse (η, η_ideal) by step S2 with the new generation grating structure obtained in steps S4 to S6;
and S8, terminating the judging condition, wherein the final grating structure meets the set coupling eta_ideal or reaches the preset number of loop iterations, and the genetic algorithm terminates and outputs the optimized grating structure.
The invention can also adopt or combine the following technical proposal when adopting the technical proposal:
as a preferable technical scheme of the invention: in step S1, the cross-sectional types of the grating include, but are not limited to, triangular, circular, square, and combinations of shapes.
As a preferable technical scheme of the invention: in step S2, the electromagnetic field simulation software selects a rigorous coupled wave analysis, a finite element or finite difference time domain method, or a combination of the above methods.
A second object of the present invention is to provide an application of a genetic algorithm for a wide-angle coupling structure, which aims at the problems in the prior art.
For this purpose, the above object of the present invention is achieved by the following technical solutions: the genetic algorithm facing the wide-angle coupling structure is applied to the microstructure optical probe.
A third object of the present invention is to provide a microstructured optical probe, which solves the problems of the prior art.
For this purpose, the above object of the present invention is achieved by the following technical solutions:
the microstructure optical probe is characterized in that: the coupling microstructure is a periodic grating structure, the periodic grating structure is formed by periodically distributing grating structures optimized by a genetic algorithm facing the wide-angle coupling structure, incident light can be coupled into an optical fiber waveguide through the grating modulation effect of the coupling microstructure, and transmitted to the other end of the optical fiber to be emitted to form emergent light, and the coupling light intensity is detected through an optical power meter, so that the wide-angle efficient coupling of the grating microstructure is realized.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a genetic algorithm, application and microstructure optical probe for a wide-angle coupling structure, which regulates and controls parameters such as grating period, grating width, material refractive index, grating height and the like for the coupling structure of the wide-angle incident optical probe through the genetic algorithm, sets an adaptability function related to diffraction order working efficiency according to various factors and requirements such as target wavelength, incident angle, waveguide structure and the like, iteratively improves diffraction order numerical values, thereby improving diffraction efficiency of specific diffraction orders, optimizing coupling efficiency and realizing efficient coupling in/out of an optical waveguide of a wide angle of light beam. The micro-structure optical probe applied to the genetic algorithm of the wide-angle coupling structure is based on the enhancement of the coupling structure, and the wide-angle coupling efficiency can reach more than 20%; the design of the high-freedom degree microstructure is oriented, and the design efficiency is improved; the structural materials, structural parameters, spatial distribution and coupling efficiency of the microstructure and the optical waveguide can be adjusted and customized according to the optical coupling scene, and the expansibility is strong. The genetic algorithm, application and microstructure optical probe for the wide-angle coupling structure provided by the invention can be used in a plurality of fields such as integrated photoelectric chips, scanning near-field microscopes, random photon signal detection, wide-angle endoscopes and the like, has the advantages of high coupling efficiency, high integrated preparation integrity, strong expansibility, wide application scene and the like, has a good development prospect, and has application prospects in the fields such as photoelectric chips, integrated optics, optical interconnection, optical fiber integrated nano sensing and the like.
Drawings
FIG. 1 is a schematic diagram of the operation of a microstructure-based enhanced optical waveguide wide-angle coupling probe according to the present invention;
FIG. 2 is a flow chart of a genetic algorithm for a wide-angle coupling structure of the present invention;
FIG. 3 is a side view (a) and a top view (b) of a ring-shaped periodic grating structure unit after genetic algorithm optimization for a wide-angle coupling structure;
FIG. 4 is a graph comparing the coupling data of the wide-angle probe based on the grating enhancement with the reported data of the literature;
in the drawings, incident light 100; a coupling microstructure 101; an optical waveguide 102; the outgoing light 103; a power meter 104; an incident angle θ105; zero order diffraction order 106; positive first order diffraction order 107.
Detailed Description
The invention will be described in further detail with reference to the drawings and specific embodiments.
The invention discloses a genetic algorithm for a wide-angle coupling structure, which comprises the following steps:
step S1, setting a grating structure coupling efficiency set value eta_ideal and the number of cyclic iterations of a genetic algorithm, inputting grating structure parameters into electromagnetic field simulation software, and taking the grating structure parameters as variables, wherein the variables comprise a period lambda, a grating width w, a grating material refractive index n_g, an incident angle theta and various parameters of a grating structure cross section;
step S2, using electromagnetic field simulation software to obtain a_ (+1) of a grating structure and coupling efficiency eta of an optical probe, taking the mean square error of the grating coupling efficiency eta and a target value eta_ideal as a fitness function, and calculating the fitness function F=MSE (eta, eta_ideal);
step S3, judging whether the coupling efficiency eta of the current grating structure reaches a set value eta_ideal, if so, directly outputting the current optimal grating structure, and if not, entering step S4;
step S4, screening operation is carried out, a new grating structure population is formed by selecting a grating structure with high coupling efficiency eta from the previous grating structures according to 50% probability, the new grating structure population is used for breeding to obtain a next generation grating structure population, and when the value of the grating coupling efficiency eta is higher than the average value eta of the coupling efficiency of the previous generation ＇ When the grating structure is determined to be a high coupling efficiency grating structure;
step S5, performing cross operation on the high coupling efficiency grating structures in step S4 to form a high coupling efficiency grating structure population, randomly selecting two or more grating structure parameters from the population, inheriting the high coupling efficiency eta characteristic of the current grating to the next generation through the exchange combination of parameter variables, and generating a new excellent grating structure combination, wherein the coupling efficiency eta of each excellent grating structure in the new excellent grating structure combination is higher than the average value eta of the high coupling efficiency grating structures 2＇ ；
S6, performing mutation operation, namely selecting the grating structure with high coupling efficiency in the step S4, and randomly changing parameters of a plurality of grating structures to generate other grating structures;
step S7, respectively obtaining a_ (+1) of each grating structure and the coupling efficiency eta of the optical probe through step S2 by using each high coupling efficiency grating structure selected in step S4, each excellent grating structure obtained in step S5 and other grating structures generated in step S6, and calculating a fitness function F=MSE (eta, eta_ideal);
step S8, when the fitness function F=MSE (eta, eta_ideal) value calculated in the step S7 is 0, judging the grating as the optimal grating, outputting the optimal grating structure, and terminating the genetic algorithm; and when the fitness function f=mse (η, η_ideal) value obtained by calculation of each grating structure in the step S7 is not 0, re-entering the step S4, and performing the operations in the steps S5, S6 and S7 until the fitness function f=mse (η, η_ideal) value obtained by calculation of the grating structure is 0, or the predetermined number of genetic algorithm loop iterations is reached.
In step S1, the cross-sectional type of the grating includes, but is not limited to, triangle, circle, square, and combinations of shapes, and the parameters of the cross-section of the grating structure include, but are not limited to, inner angle, side length, radius, arc length;
when the cross section of the grating structure is triangular, each parameter of the cross section of the grating structure comprises an inner angle and each side length;
when the cross section of the grating structure is circular, each parameter of the cross section of the grating structure comprises a radius;
when the cross section of the grating structure is square, each parameter of the cross section of the grating structure comprises a side length;
when the cross section of the grating structure is trapezoidal, each parameter of the cross section of the grating structure comprises an inner angle and each side length;
when the cross section of the grating structure is arc-shaped, each parameter of the cross section of the grating structure comprises an inner angle, each side length and an arc length.
FIG. 2 is a genetic algorithm for a wide-angle-coupling-oriented structure for coupling structure optimization design of the present invention. The genetic algorithm is an optimization method widely applied to the fields of machine learning, signal processing, self-adaptive control and the like, is designed by simulating the biological evolution rule in the nature, and comprises the following specific processes: data input- > fitness function calculation- > screening- > crossing- > mutation- > termination condition judgment- > final structure.
The key step of the genetic algorithm of the wide-angle incident light probe coupling structure shown in fig. 2 is to calculate the fitness function f=mse (η, η_ideal) by using electromagnetic field simulation software such as Rigorous Coupled Wave Analysis (RCWA), finite Element (FEM), finite difference time domain method (FDTD). In general, grating structure parameters including, for example, height H, period Λ, width w, etc., can be input into the electromagnetic field simulation tool as above, and the simulation modeled, resulting in a_ (+1) of the grating structure and the coupling efficiency η of the optical probe. Here, taking a 50 ° incidence, the target optical probe coupling efficiency η_ideal is set to 0.5 as an example, and the fitness function is thus defined as f=mse (a_ (+1), 0.5). Then, parameters such as the height H, the period lambda, the width w and the like of the grating structure can obtain corresponding fitness functions through steps such as screening, crossing, mutation and the like in a genetic algorithm. And selecting and retaining grating parameters meeting the coupling value target or approaching the coupling value in the samples, and entering the steps of screening, crossing, mutation and the like of the next round. Until the final structure meets the set coupling eta_ideal or the preset loop iteration times are reached, the genetic algorithm is not stopped and the optimized grating structure is output.
The genetic algorithm for the wide-angle coupling structure is used for designing the periodic grating of the wide-angle incident light probe. The periodic grating is composed of a periodically arranged grating structure. Specifically, the plurality of grating units form an array structure or a ring structure through the modes of periodic arrangement, stretching, rotation and the like. In this embodiment, only the parameters of a single grating unit will be considered for simplicity. Taking a coupling grating with a rectangular cross section as an example, grating structure variables include grating height H, period Λ, grating width w, grating material refractive index n_g, incidence angle θ, etc. as system variables. Different combinations of the above parameters may change the target diffraction order a_ (+1) value.
The cross-section type of the grating is not limited in the invention, and the grating can be rectangular, trapezoidal, triangular, round, square and the like and the combination of the shapes can be included.
As shown in fig. 1, the genetic algorithm for the wide-angle coupling structure of the present invention is applied to a wide-angle coupling microstructure optical probe, which comprises a coupling structure 101 and an optical waveguide 102. The optical waveguide substrate can adopt optical fibers, which are fibers made of glass or plastic or other composite materials, and the point-to-point transmission of light is realized by utilizing the principle of total internal reflection of the light. The working principle of the optical probe is as follows: when the incident light 100 is incident at the incident angle theta 105, the positive first-order diffraction order 106 of the incident light can be coupled into the optical fiber waveguide 102 through the grating modulation effect of the coupling microstructure 101, and transmitted to the other end of the optical fiber to be emitted, and the emitted light 103 is emitted, and the coupled light intensity is detected through the optical power meter 104. The coupling efficiency can be evaluated for the light collection performance of the optical probe, and is generally defined by the ratio of the outgoing light 103 to the incoming light 100.
The genetic algorithm for the wide-angle coupling structure is used for designing a periodic coupling grating structure of a wide-angle incident light probe. The periodic grating is composed of periodically arranged grating units.
According to the periodic grating structure, parameters such as grating period, grating width, material refractive index, grating height and the like are regulated and controlled through the genetic algorithm facing the wide-angle coupling structure, so that diffraction efficiency of a specific diffraction order is improved, and efficient coupling of a wide angle of a light beam into/out of the optical waveguide is realized.
Specifically, a plurality of grating units form a grating structure, and the grating structure forms an array structure or an annular structure through the modes of periodic arrangement, stretching, rotation and the like. According to the genetic algorithm, an fitness function related to the diffraction order working efficiency is set according to various factors and requirements such as target wavelength, incidence angle, waveguide structure and the like, diffraction order numerical values are iteratively improved, and coupling efficiency optimization is carried out.
The optimized coupling grating can be prepared on the end face or the side face of the optical waveguide by micro-nano processing methods such as electron beam lithography, two-photon polymerization and the like, so that efficient coupling in/coupling out of light is realized.
The invention relates to an optical waveguide wide-angle coupling probe applied to a genetic algorithm of a wide-angle coupling structure, which has the working principle that: incident light 102 enters the optical waveguide 101 at an incident angle theta 105, and is coupled to the microstructure 100, and the incident light can be modulated to generate diffracted waves such as zero order 105 and positive first order 104, and diffraction efficiencies of the diffracted waves correspond to a_0105 and a_ (+1) 104, respectively. Particularly, at the time of large angle incidence, for example, θ >30 °, the coupling efficiency at the time of wide angle incidence is improved by increasing a_ (+1) 104 to a certain value such as a_ (+1) =1. The coupling structure 100 and the optical waveguide 101 shown in fig. 1 are used as schematic diagrams only.
In the present invention, the dimension of the coupling microstructure is adapted to the target optical waveguide, for example, the end face of the circular optical fiber, the typical radius dimension is hundreds of nanometers to hundreds of micrometers, the morphology is a 2D or 3D three-dimensional structure, and the constituent materials can be metal, dielectric, polymer materials, or a combination of the above materials.
In the present invention, the optical waveguide may be a single mode optical fiber, a multimode optical fiber, a multi-core optical fiber, or the like, or a combination of the above optical fibers, or an on-chip optical waveguide, or a combination of the above plural types of waveguides.
The invention has the outstanding advantages that: based on the genetic algorithm for the wide-angle coupling structure, the genetic algorithm for the high-freedom coupling microstructure application scene improves the design efficiency; based on the micro-nano structure reinforced optical waveguide probe, the wide-angle coupling efficiency can reach more than 15%; the structural materials, structural parameters, spatial distribution and coupling efficiency of the microstructure and the optical waveguide can be adjusted and customized according to the optical coupling scene, and the expansibility is strong.
The optical waveguide wide-angle coupling probe applied to the genetic algorithm oriented to the wide-angle coupling structure provided by the invention can be used in a plurality of fields such as an integrated photoelectric chip, a scanning near-field microscope, random photon signal detection, a wide-angle endoscope and the like, has the advantages of high coupling efficiency, high integrated preparation integrity, strong expansibility, wide application scene and the like, has a good development prospect, and has application prospects in the fields such as photoelectric chips, integrated optics, optical interconnection, optical fiber integrated nano sensing and the like.
Example 1
The invention relates to a microstructure reinforced optical waveguide probe optimized by genetic algorithm for a wide-angle coupling structure, which takes single-mode communication optical fiber SMF-28 as a use case. Fig. 3 shows a periodic grating coupling structure with a trapezoidal cross section. The side view is shown in fig. 3 (a), the period of the trapezoid is 2.1 μm, the height is 1.6 μm, and the internal angle is 85 °. Fig. 3 (b) shows a top view of a grating fabricated on the end face of an SMF-28 fiber, with the overall multilayer annular morphology. Note that the ring grating is obtained by rotating the periodic structure in (a) in fig. 3 by a coaxial plane. The probe adopts a two-photon three-dimensional optical preparation method, namely a two-photon laser direct writing technology, is integrally formed, has the composition of a high polymer, and has the advantages of high Young modulus, high integration level, high preparation freedom degree and the like. As can be seen from fig. 3 (b), the structure surface is flat, has a fine roughness, and conforms to the original design dimensions.
Fig. 4 shows the wide angle coupling data of the fiber optic probe shown in fig. 3. The abscissa is the incident angle θ and the ordinate is the coupling efficiency amplitude. In this figure, the solid and dashed lines represent the microstructure reinforced optical fiber and the reference structure, respectively, reference ACS Photonics 7 (10), 2834-2841. It can be seen from the graph that the coupling efficiency of the optical fiber enhanced by using the trapezoidal grating is improved to 27% at the incidence angle of 30-60 degrees, which exceeds the coupling efficiency of the optical fiber of about 14% of the coupling structure disclosed in the prior art. The wide angle referred to in the present invention means that the incident angle θ is >20 °.
The above detailed description is intended to illustrate the present invention by way of example only and not to limit the invention to the particular embodiments disclosed, but to limit the invention to the precise embodiments disclosed, and any modifications, equivalents, improvements, etc. that fall within the spirit and scope of the invention as defined by the appended claims.

Claims (5)

1. A genetic algorithm for a wide-angle coupling structure, comprising the steps of:
step S1, using the height H, the period lambda, the grating width w, the refractive index n_g of a grating material and the incident angle theta in a grating structure as variables, using the mean square error of the grating coupling efficiency eta and a target value eta_ideal as an fitness function, and changing the value of a target diffraction order a_ (+1) and the coupling efficiency eta of the optical probe through different combinations of parameters of each grating structure;
step S2, using electromagnetic field simulation software to obtain a_ (+1) of the grating structure and the coupling efficiency eta of the optical probe, and calculating a fitness function F=MSE (eta, eta_ideal);
step S3, judging whether the coupling efficiency eta of the current grating structure reaches a set value eta_ideal, if so, directly outputting the current grating structure, and if not, entering step S4;
step S4, screening operation is carried out, and a new grating structure population is formed by selecting a grating structure with high coupling efficiency eta from the previous grating structures according to 50% probability so as to reproduce and obtain a next generation grating structure population, wherein the grating structure with high coupling efficiency eta refers to a grating structure with the average value eta' of the coupling efficiency of the previous generation;
step S5, performing cross operation, randomly selecting two or more grating structure parameters from a grating population, inheriting the high coupling efficiency eta characteristic of the current grating to the next generation through the exchange combination of parameter variables, thereby generating a new excellent grating structure combination, wherein the coupling efficiency eta of the new excellent grating structure is higher than the average value eta' of the coupling efficiency of the previous generation;
s6, performing mutation operation, wherein in the current grating population, parameters or parameter combinations of a certain grating structure are randomly changed so as to expect to generate more grating structures;
step S7, calculating a fitness function f=mse (η, η_ideal) by step S2 with the new generation grating structure obtained in steps S4 to S6;
and S8, terminating the judging condition, wherein the final grating structure meets the set coupling eta_ideal or reaches the preset number of loop iterations, and the genetic algorithm terminates and outputs the optimized grating structure.
2. The wide-angle-coupling structure-oriented genetic algorithm of claim 1, wherein: in step S1, the cross-sectional types of the grating include, but are not limited to, triangular, circular, square, and combinations of shapes.
3. The wide-angle-coupling structure-oriented genetic algorithm of claim 1, wherein: in step S2, the electromagnetic field simulation software selects a rigorous coupled wave analysis, a finite element or finite difference time domain method, or a combination of the above methods.
4. Use of a genetic algorithm for a wide-angle-coupling structure according to any of claims 1-3 for microstructured optical probes.
5. The microstructured optical probe of claim 4, wherein: the coupling microstructure is a periodic grating structure, the periodic grating structure is formed by periodically distributing grating structures optimized by a genetic algorithm facing the wide-angle coupling structure, incident light can be coupled into an optical fiber waveguide through the grating modulation effect of the coupling microstructure, and transmitted to the other end of the optical fiber to be emitted to form emergent light, and the coupling light intensity is detected through an optical power meter, so that the wide-angle efficient coupling of the grating microstructure is realized.
CN202310755376.2A 2023-06-26 2023-06-26 Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure Active CN116502545B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310755376.2A CN116502545B (en) 2023-06-26 2023-06-26 Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310755376.2A CN116502545B (en) 2023-06-26 2023-06-26 Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure

Publications (2)

Publication Number Publication Date
CN116502545A true CN116502545A (en) 2023-07-28
CN116502545B CN116502545B (en) 2023-09-26

Family

ID=87325108

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310755376.2A Active CN116502545B (en) 2023-06-26 2023-06-26 Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure

Country Status (1)

Country Link
CN (1) CN116502545B (en)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1570687A (en) * 2004-05-09 2005-01-26 上海理工大学 Waveguide-optical fiber automatic core adjusting method based on genetic algorithm and device thereof
CN101477224A (en) * 2009-01-20 2009-07-08 南京航空航天大学 Bragg optical grating axial heterogeneous strain reconstruction method based on genetic planning
CN108734292A (en) * 2018-05-04 2018-11-02 浙江大学 The optimization method and inclined surface relief grating waveguide display systems of multi-disc inclined surface embossment jointing grating based on genetic algorithm
CN110764255A (en) * 2019-10-21 2020-02-07 天津大学 Design and optimization method of waveguide display sub-wavelength diffraction grating
US20210063894A1 (en) * 2019-09-02 2021-03-04 Asml Netherlands B.V. Mode control of photonic crystal fiber based broadband radiation sources
WO2022179534A1 (en) * 2021-02-24 2022-09-01 The Chinese University Of Hong Kong High coupling efficiency blazed waveguide grating coupler
CN115268065A (en) * 2022-06-06 2022-11-01 北京理工大学 Particle swarm-based two-dimensional diffraction waveguide display system and uniformity optimization method thereof
CN115933063A (en) * 2022-12-12 2023-04-07 中国科学院上海微系统与信息技术研究所 Variable-period grating coupler based on genetic algorithm optimization

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1570687A (en) * 2004-05-09 2005-01-26 上海理工大学 Waveguide-optical fiber automatic core adjusting method based on genetic algorithm and device thereof
CN101477224A (en) * 2009-01-20 2009-07-08 南京航空航天大学 Bragg optical grating axial heterogeneous strain reconstruction method based on genetic planning
CN108734292A (en) * 2018-05-04 2018-11-02 浙江大学 The optimization method and inclined surface relief grating waveguide display systems of multi-disc inclined surface embossment jointing grating based on genetic algorithm
US20210063894A1 (en) * 2019-09-02 2021-03-04 Asml Netherlands B.V. Mode control of photonic crystal fiber based broadband radiation sources
CN110764255A (en) * 2019-10-21 2020-02-07 天津大学 Design and optimization method of waveguide display sub-wavelength diffraction grating
WO2022179534A1 (en) * 2021-02-24 2022-09-01 The Chinese University Of Hong Kong High coupling efficiency blazed waveguide grating coupler
CN115268065A (en) * 2022-06-06 2022-11-01 北京理工大学 Particle swarm-based two-dimensional diffraction waveguide display system and uniformity optimization method thereof
CN115933063A (en) * 2022-12-12 2023-04-07 中国科学院上海微系统与信息技术研究所 Variable-period grating coupler based on genetic algorithm optimization

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
I-CHOU WU: "Optical Side-Coupling of Laser-Diode Array to Fiber using Genetic Algorithm Designed Sub-Wavelength Grating", 《2018 23RD OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC)》 *
陈琪;李国俊;方亮;周崇喜;: "亚波长多台阶结构大角度激光分束器设计", 中国激光, no. 02 *

Also Published As

Publication number Publication date
CN116502545B (en) 2023-09-26

Similar Documents

Publication Publication Date Title
KR20200141443A (en) Diffraction grating containing a dual material structure
JPH11218641A (en) Optical fiber with lens and laser module
CN113568076B (en) Double-function superlens and optical rotation detection method
CN113835158B (en) Free space light and photon chip end face coupling method
CN108227188A (en) A kind of complete random silica-based waveguides grating design method based on Chaos particle swarm optimization algorithm
CN117420633B (en) Optical fiber probe based on composite micro-nano grating structure
CN116502545B (en) Genetic algorithm, application and microstructure optical probe for wide-angle coupling structure
CN102737713B (en) Based on the two-dimentional integrated form optical fiber on-line memory of linear array multi-core fiber
Delâge et al. Monolithically integrated asymmetric graded and step-index couplers for microphotonic waveguides
CN102109635B (en) Method for writing and manufacturing laser pulse of tilt long period and ultra-long period fiber grating
TWI447453B (en) Optical star coupler
EP1481272A1 (en) Device for bending an optical beam, in particular in an optical integrated circuit
Zubia et al. Barrier sensor based on plastic optical fiber to determine the wind speed at a wind generator
CN113673677B (en) Method, equipment and medium for realizing nonlinear activation function RELU
CN113296184B (en) Polymer micro-nano optical fiber of bridge-type cross structure based on cosine bending
CN114815057A (en) Focusing type vertical grating coupler and preparation method thereof
CN111090147A (en) Integrated optical waveguide integrated with periodic array of nano-structure
Ogata et al. Side edge emission from a waveguide substrate
CN115808738B (en) Middle-infrared grating coupler based on single annular structure and simulation method thereof
CN111025482A (en) Mode efficient coupler and preparation method thereof
Park et al. Ray model of an incident Gaussian beam for analyzing a micro-optical communication device with a GRIN lens system
CN117250690B (en) Optical field focusing method and device for on-chip waveguide integration
Zhou et al. Fabrication and experimental characterization of precise high-efficiency 2D multi-mode fiber array coupler
CN112630882B (en) Multi-core annular optical fiber and quantum system comprising same
US11137538B2 (en) Multicore ring fibers and quantum systems comprising such fibers

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant